A four year program is proposed to construct a laser flying-spot phase modulation microscope for biomedical research. (1) A laser flying-spot (scanning) microscope makes it possible to obtain diffraction limited video images through the microscope in any mode of operation (phase contrast, DIC, fluorescence, etc.) by circumventing the limiting factor in the quality of microvideo images: the video camera. (2) An updated, vastly improved phase modulation system based on new circuit design concepts and isotopic PLZT ceramic modulators will add new dimensions of versatility, sensitivity, speed, accuracy and stability to polarization and interference microscopy. (3) When a phase modulation system is used to filter flying spot video images, the result will be modal video images expressed in a selected optical property of the specimen. The grey scale information can be manipulated by synchronous detector sensitivity within the limits set by photon noise, and resolution will remain diffraction limited. By altering the sequence of optical components in the microscope, any of ten optical properties can be measured selectively in images by appropriate videoslice techniques.